The present invention relates to a novel compound useful for preparing antibacterial benzoxazine derivatives. More particularly, the present invention relates to 2-benzoyl-3-aminoacrylate derivatives represented by the following general formula I and the method for preparing the same. ##STR2## wherein X is a halogen;
X.sub.l and X.sub.2 are independently selected from a halogen and a nitro; and PA1 R, R.sub.1 and R.sub.2 each is an alkyl group containing 1 to 4 carbon atoms.
The compound of formula I of the present invention can be used as a starting material for preparing antibacterially active benzoxazine derivatives of the following formula VIII which in turn serves as an intermediate for synthesizing a potent antibacterial compound ofloxacin (Chem. Pharm. Bull, 32, 4907-4913 (1984): ##STR3## wherein X and R are as defined hereinabove.
Further, in Korean Patent Application No. 94-5975 to the present inventors, applied on Mar. 24, 1994, an improved method for the preparation of the aforementioned compound of formula VIII was suggested, using the subject compound of formula I.
2. Description of the Prior Art
Conventionally, there has been provided a compound of formula 3 as an intermediate for the preparation of the benzoxazine derivatives. However, it needs many steps to obtain the compound of formula 3 such as reacting 2, 3, 4, 5-tetrafluoro benzoyl chloride 1 with ethyl ethoxymagnesium malonate and further reacting the resulted ethyl (2,3,4,5-tetrafluorobenzoyl)acetate 2 with triethyl orthoformate/acetic anhydride and then substituting the obtained compound with 2-amino-1-propanol to obtain the compound of formula (see M. Schriewer, K. Grohe, H. J. Zeiler and K. G. Hetzger, German Offen. DE 3,543,513 (1987); Chem. Abstr., 107, 154342c (1987); L. A. Mitscher, P. N. Sharma, D. T. W. Chu., L. L. Shen and A. G. Pernet, J. Med. Chem. 30, 2283 (1987)). Further, it is another problem of the obtained compound of formula 3 being not sufficiently stable and difficulty of handling thereof. ##STR4##